1. Field of the Invention
The present invention relates generally to devices for engaging heavy or cumbersome loads, for example, rooftop heating, ventilating and air conditioning (xe2x80x9cHVACxe2x80x9d) units prior to lifting the load off of a surface. More specifically, the invention relates to such devices which include wheels or casters, legs or support channels so that the load can be lifted, repositioned, lowered into place or secured to other objects.
2. Description of Prior Art
There is a plethora of prior art devices adapted to lift and reposition loads. Cranes, fork trucks, lift gates, carts, and scaffolding devices have all been used to reposition large loads. Generally, the most popular method is by the use of a crane. In almost every case, the prior art utilizes a means of gripping the load, lifting the load and repositioning the load, all supported by the framework and/or mass of the lifting device itself. For example, a crane includes a cable supported on an arm or a boom, means for connecting the cable to the load, and means for taking up or paying out cable as needed. The lifting of the load and repositioning of the load is completed by the mass and or framework of the lifting device. Cranes are often used to position large loads such as HVAC equipment on a roof. Coordination of delivery of HVAC equipment on a truck and the crane for lifting the load off of the truck can be difficult and often costly. If coordination of the two events does not coincide in time, a crane must be brought back to the site, at an added cost, to put the HVAC equipment into final position. Even helicopters have been used to position. such equipment.
The present invention is based upon the discovery of a device comprising a frame that can be operated to engage an apertured rail secured to a large load, such as HVAC equipment, so that the frame and the load can be lifted and moved. Typically, such rails include apertures for receiving the forks of a forklift truck or the lifting lugs of a crane. The device can accommodate a load without apertured rails if apertures are formed at the base of the load. A device according the present invention comprises a frame member having a rail or load face, at least one pair of jaws supported on said frame member and a jaw positioner operably connected to position the jaws in a first position, in which said jaws can be inserted into one or more openings a rail connected to a load, and operable to position the jaws in a second position, in which the jaws engage a portion of the rail and cause the rail or load face of the frame member to abut the rail or load, thereby locking the frame member to the rail or load. The frame is designed to cooperate with at least one wheel, caster, leg or support channel, securable to the frame member and a frame lifter operable to raise and lower the frame member relative to the wheel, caster, leg or support channel. In a preferred embodiment, the frame member is designed to cooperate with a pair of wheels or casters at opposite ends of the frame member, each including a frame lifter.
When a desired number of the frame members have been secured to the load or to rails under a load, (the rails generally being an integral part of the load to be repositioned) the frame lifters can be connected to the frame and actuated to raise the frame and the rails and the load so that they are supported on the wheels or casters. The load can then be maneuvered by one or more individuals or by other mechanical means to a desired location where the frame lifters are again actuated to lower the frame members and the load into place. Once the load is in place, the jaw positioners of the devices are actuated to return the jaws to the first position so that the frame member may be removed from one load and secured another.
The frame member is portable and is small enough and light enough that it can easily be transported to a roof for lifting, supporting and repositioning large loads including HVAC units. In a preferred embodiment, the device is also assembled from a plurality of modules, so that it can be disassembled into the modules, transported, and then reassembled for use in a new location. The device also has utility in the manufacture and transportation of HVAC units or other large pieces of machinery and can be utilized to move HVAC units or other machinery from station to station in the assembly operation used in manufacturing thereof.
Accordingly, it is an object of the present invention to provide a device for engaging a large load, especially one supported on rails or the like.
It is a further object of the invention to provide a device which can be positively locked to or unlocked from the load or a rail attached to a load.
It is a primary object of this invention to provide a device including a frame member which can be locked to a large load and cooperate with frame lifters for raising the frame member and the rail and the load and supporting the load on wheels, casters, legs or support channels that are secured to the frame member.
These and other objects and advantages over the present invention will no doubt become apparent to those skilled in the art after having read this detailed description of the invention including the following description of the preferred embodiment which is illustrated by the various figures of the drawing.